One apparatus has been proposed to test a single-connector harness by supplying substantially identical oscillatory signals to the arms of a two-arm bridge circuit, the arms of which are connected to respective inlets of a different amplifier, the arms being grounded through capacitances and a ground plane existing in the vicinity of the lead. Continuity between an electrically connected terminal and wire core unbalances the signal inputs supplied by the bridge circuit to the differential amplifier to emit a continuity test signal. Reference may be made to U.S. Pat. Nos. 4,654,580 and 4,734,651.
The testing apparatus proposed in the above patents inherently is subject to error due to imbalances induced in the bridge circuit by changes in temperature of the proposed apparatus in the work environment, thus means must be provided to balance the bridge circuit prior to each continuity test. In addition, the use of the machine and operator as a natural ground plane may also introduce other variables that may unintentionally unbalance the bridge circuit and provide a false indication of continuity.
In order to test a wire harness the terminal test probes utilized in the apparatus of the above patents are laterally inserted into special windows in a connector wall to engage the terminals of the connector. Thus, the propose apparatus does not disclose an apparatus capable of concurrently terminating and testing connectors not having lateral access windows formed in a manner allowing accurate engagement of the connector terminals by the test probes. In addition, the probes of this apparatus do not engage the contact portion of the connector terminals and thus the apparatus does not test the mechanical and electrical integrity of the contact portion of the connector terminal in a manner simulating actual mating engagement between the contact portions and a male connector.